Brush-holder.



PATENTBD JUNE 30, 1903. I L. E. UNDERWOOD.

BRUSH HOLDER.

APPLICATION FILED MAY 19. 1902.

N0 MODEL.

lnvenfior.

Louis EU Winesses,

n der'wood.

m: cams PETERS c6. mumumm WASHINGTON. ay 0 two springs.

UNITED STATES Patented June 30, 1903.

PATENT OFFICE.

LOUIS E. UNDERVVOOD, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEWV YORK.

BRUSH-HOLDER.

SPECIFICATION forming part of Letters Patent No. 732,240, dated June 30,1903.

Application filed May 19, 1902- Serial No. 107,914. (No model.)

To all whom it may concern:

Be it known that I,LoUIs E. UNDERWOOD, a citizen of the United States,residing at Lynn, county of Essex, State of Massachu- 5 setts, haveinvented certain new and useful Improvements in Brush-Holders, of whichthe following is a specification.

My invention relates to brush-holders for dynamo-electric machines,motors, and the to like apparatus, and has more particular reference tobrush-holders of the reaction type.

The object of my invention is to provide an improved and compactconstruction of the brush-holder in which the pressure upon the :5 brushin the direction of commutation and the pressure in the directiontransverse thereto to hold it against its guide-surface shall maintain adefinite relation to each other regardless of the amount of suchpressure and also maintain a uniform resultant pressure of the brush onthe commutator.

To this end my inventionconsists in an improvement upon the device of E.W. Rice, Jr., patented April 29, 1890, No. 426,471, wherein the holderis carried by a spring-pressed lever and the brush is pressed in thedirection of commutation byaspring thrusting against its end and theunder side of the lever and in transverse direction against itsguide-suro face by a roller carried upon a spring extension of saidlever; but in this construction the transverse pressure is substantiallyuniform, While the pressure upon the end of the brush is kept onlypartially uniform by the I provide two independent levers, one to applythe transverse pressure and the other the longitudinal pressure to thebrush, and connect them by a single spring, which allows one of thelevers to move 0 while the other remains substantially stationary, andby locating the point of attachment of the spring to the lever exertingthe longitudinal pressure so that the arm of the movement shall increaseas the spring con- 5 tracts with the shortening of the brush a uniformresultant pressure is maintained between brush and commutator.

My invention will be more readily understood by reference to theaccompanying drawings, in which Figure 1 is a longitudinal verticalsection of a brush-holder embodying my improvements. Fig. 2 is a plan ofthe same, and Fig. 3 is a vertical section on line 3 3 ofFig. 2.

The modification shown in the drawings comprises a guide-box A, the sideportions 2 of which have offsets 3 near one end and depending extensions4 at their lower edges to provide additional width at the brush end. Theupper rear corners of the side portions are cut away, and a bar 5connects their lower corners. A shield 6 connects the rear corners ofthe dependingside extensions 4 and serves to protect theantifriction-rollagainst sparking, and the long bearing-plate 7 connectsthe front ends of said side portion 2. A lug or projection 8 from one ofthe side portions is provided with means whereby the brushholder may beattached to a suitable support.

My improved brush-holder may be used for holding radial brushes orangular brushes of the character shown at 9. With the constructionillustrated in Fig. 1 the brushholder operates satisfactorily, whetherthe commutator rotates in one direction or the other.

In order to admit brushes which difler slightly in thickness and also tocompensate for slight irregularities in the brushes, the recess betweenthe shoulders 10 of the offsets 3 and the bearing-surface of the end 7is made wider than the thickness of the brush. Thetransversely-operating lever 11 for holding the brush 9 normally incontact with the bearing-plate 7 is pivoted upon a shaft 12, carried inthe side portions 2 near their upper edges and in proximity to theshoulders 10 and carries at its lower end a contact device, preferablytaking the form of an antio friction-roll 13, which bears against theside of the carbon brush 9 and is held in engagement therewith by theaction of the'spring 14, engaging the upper end of the lever. The otherend of the spring 14 engages the crossbar 15 at the rear end of thearc-shaped arms 16 of the lever B, which operate to press the brushlongitudinally into contact with the commutator. The arms 16 areconnected at their front ends by a bar 17, which rests upon I00 theupper end of the brush, and are also connected at a point intermediatetheir ends by the handle-bar 18. The main longitudinallyacting lever Bispivoted to the inner faces of the side portions 2 by rivets orstub-shafts 19, extending through said side portions and the rear endsof the arms 16. The rivets or stubshafts 19 are so positioned withrelation to the rear bar 5 that the cross-bar 15, to which the spring isattached, will be carried beyond the dead-center when the lever isthrown back against the bar 5, as indicated in the right-handdotted-line position, Fig. 1, and thereby the lever B may be securelyheld out of the way when renewing the brush. Moreover, the cross-bar 15is positioned with relation to the pivot-points 19 so that when thelever B is pressing upon a long brush the said bar 15 stands beyond thepivots 19, and the line along which the force of the spring acts iscorrespondingly nearer the pivotpoints than when the brush and springhave become shortened. By reason of the arc shape of the lever B thefront end is adapted to follow the brush a considerable distance belowthe axis of the transversely-acting lever 11 without engaging therewith.

It will be observed that in the arrangement herein described there is notendency for the brush to stick upon its guide by reason of thetransverse pressure thereon being too great relatively to the pressureacting longitudinally thereon. When the tension of the spring is varied,as by movement of lever B to innermost position, both levers areaffected alike, and the ratio of their pressures remains unchanged.

In order that a worn-out brush may be removed from the holder, I provideslots 20 in both of the offset portions 3, which extend into thebrush-recess, as shown in Fig. 3, whereby the edges of the brush areexposed, so as to be grasped by the fingers and raised.

I wish it understood that my invention is not limited to the speci ticconstruction shown.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In a brush-holder, the combination of a guide-box, a main lever forpressing the brush longitudinally pivotally mounted within said box, asecond lever having an antifrictionroll adapted to engage and press thebrush transversely, and a spring connecting said levers.

2. In a brush-holder, the combination of a guide-box, a lever pivotedwithin said box and adapted to bear upon the brush in a longitudinaldirection, a second lever pivoted upon said box beneath the first leverand adapted to bear upon the brush in a transverse direction, and meansfor maintaining a uniform ratio of pressure upon said levers.

3. In a brush-holder, the combination of a guide-box, a lever pivotedwithin said box and adapted to force the brush toward the commutator, asecond lever pivoted within said box and having an antifriction rolladapted to bear upon the side of the brush, and a spring connected atits respective ends to said levers and operating to maintain a uniformratio of pressure upon said levers.

4. In a brush-holder, the combination of a box having a guideway at oneend in which the brush may move in a longitudinaldirection, a leverpivoted near the opposite end of.

said box and adapted to bear upon the end of the brush, a second leverpivoted near the guideway and adapted to bear upon the side of thebrush, and a spring connecting said levers.

5. A brush-holder box having finger slots or recesses extending throughits side Walls into the guideway for the brush.

6. A brush-holder box having ,a substantially inclosed guideway for thebrush, and elongated finger slots or recesses 20 extending through thesides into said guideways.

7. In a brush-holder, the combination of a box, a lever pivoted uponsaid box, and having its free end extended into proximity to thecommutator, and adapted to bear upon the side of the brush, and aprotecting-shield on the box between the lever and the commutator.

In witness whereof I have hereunto set my hand this 16th day of May,1902.

LOUIS E. UNDERWOOD.

Witnesses:

ALEX. F. MACDONALD, DUGALD MoK. MOKILLOP.

